If you go back a century in Europe, all over the place people were speaking different languages. There were dozens of languages in France and Italy, and they're all called French [and Italian], but they were not mutually comprehensible. They were different languages. And they have mostly disappeared in the last century or so. Some are being preserved, like Welsh, some are being revived, like Basque or Catelan to some extent. There are plenty of people in Europe who can't talk to their grandmother because they talk a different language.